Why is it impossible to override a getter-only property and add a setter? [closed]

Answer 1

Because that would break the concept of encapsulation and implementation hiding. Consider the case when you create a class, ship it, and then the consumer of your class makes himself able to set a property for which you originally provide a getter only. It would effectively disrupt any invariants of your class which you can depend on in your implementation.

Answer 2

Here is a work-around in order to achieve this using Reflection:

var UpdatedGiftItem = // object value to update;

foreach (var proInfo in UpdatedGiftItem.GetType().GetProperties())
{
    var updatedValue = proInfo.GetValue(UpdatedGiftItem, null);
    var targetpropInfo = this.GiftItem.GetType().GetProperty(proInfo.Name);
    targetpropInfo.SetValue(this.GiftItem, updatedValue,null);
}

This way we can set object value on a property that is readonly. Might not work in all the scenarios though!

Answer 3

You could perhaps go around the problem by creating a new property:

public new int Bar 
{            
    get { return 0; }
    set {}        
}

int IBase.Bar { 
  get { return Bar; }
}

Answer 4

Because at the IL level, a read/write property translates into two (getter and setter) methods.

When overriding, you have to keep supporting the underlying interface. If you could add a setter, you would effectively be adding a new method, which would remain invisible to the outside world, as far as your classes' interface was concerned.

True, adding a new method would not be breaking compatibility per se, but since it would remain hidden, decision to disallow this makes perfect sense.